Educate me

Prospect

So I see people, super collectors, with things in their sigs saying 196/2523, etc, etc. How are they coming up with a list of all of the available cards for a particular player? I mean, is it as simple as doing a search for a players name in the Beckett online guide and seeing how many results come up or am I missing some kind of cataloging system that others are aware of and I'm not. Just curious.